PHYTOCHEMICAL SCREENING OF PSIDIUM GUAJAVA BARK AND IN VITRO ANTIOXIDANT ACTIVITY OF PSIDIUM GUAJAVA BARK TANNINS

Objective: Medicinal plants have been used in primary health care over many centuries before the advent of modern medicine. Psidium guajava is one of the important medicinal plants having many therapeutic uses. The present study deals with phytochemical investigations of Psidium guajava bark and in vitro antioxidant activities of Psidium guajava bark tannins.Method: Acetone, Ethanol and Water extracts of Psidium guajava bark were assessed for the phytochemical screening. Extraction of tannin from guava bark was assessed using a cold extraction method. Total phenolic content was estimated using Folin-Ciocalteau's method. Tannin was estimated using Folin-Denis method. The antioxidant activity was determined by measuring the scavenging activity of 2,2-diphenyl-1-picryl-hydrazyl (DPPH), Nitric oxide radical, super oxide radical activity and Neutrophil-MTT assay. Ascorbic acid and Butylated hydroxytoluene (BHT) were used as standard drugs for the antioxidant studies. Results: The phytochemical analysis of guava bark revealed the presence of tannins, flavonoids, saponins, glycosides and phenols in all three bark extracts (Acetone, Ethanol and Water). The bark tannin extract possessed strong scavenging activity against DPPH, Nitric oxide radical, super oxide radical and Neutrophil-MTT assays, IC50 values were 31.94 mg/ml, 54.37mg/ml, 19.04 mg/ml and 95.41 mg/ml respectively. Conclusion: From the results, it may be concluded that tannins present in the bark of Psidium guajava may be responsible for the antioxidant activity and has promising therapeutic potential, its pharmacological properties which if properly harness can be used in the management of various diseases and can serve as a base for the development of novel potent drug. Keywords: Medicinal plants, Psidium guajava, tannins, antioxidants, neutrophil-MTT assay